Hi Arturo
what exactly do you need? There is no concept of Sub Account, but the breakdown of a GL is what you call a sub ledger (Ar or Ap)
For eg- you wnt to maintain your fixed deposits in Sap. Instead of posting them in a GL, you can have one Vendor master for each FD, all of them linked to same recon account. This way you achieve the breakdown of GL account
Ajay M